Spectral Autonomy

What MOSA Actually Requires

Part of the Open Architecture Field Guide. All information is derived from unclassified, publicly releasable (Distribution A) sources.

MOSA, the Modular Open Systems Approach, is a requirement written into U.S. law (10 U.S.C. §§4401–4403). It directs defense programs to build with modular designs and open interfaces, but it names no specific standard. Programs satisfy MOSA through the standards and reference architectures in this collection. It is owned by the Office of the Under Secretary of Defense for Research and Engineering.

What it is, and what it is not

MOSA is often spoken of as something a program builds. It is more accurate to say it is something a program satisfies. MOSA is codified at 10 U.S.C. sections 4401 through 4403, and it directs that major programs use modular open systems, with interfaces that follow widely supported, consensus-based standards. The statute does not specify which standard or which architecture. It requires that the interfaces be modular, documented, and open, and it leaves the choice of how to a program.

That distinction matters for reading the rest of this landscape. SOSA, FACE, OMS, the Government Reference Architectures, and the others are not derived from MOSA in a chain. They are independent standards a program selects to satisfy the MOSA requirement. A program can meet MOSA through a reference architecture, or through open standards without a formally named one.

The five pillars

DoD frames MOSA as five pillars: establish an enabling environment, employ modular design, designate key interfaces, select consensus-based open standards, and certify conformance. The fifth is easy to overlook and is treated as co-equal: a design that claims to be open is verified against the standard, not taken on assertion.

The five pillars of MOSADoD frames MOSA as five pillars: establish an enabling environment, employ modular design, designate key interfaces, select consensus-based open standards, and certify conformance. All five rest on the statutory requirement at 10 U.S.C. sections 4401 through 4403.1Enablingenvironment2Modulardesign3Keyinterfaces4Openstandards5CertifyconformanceMOSA · 10 U.S.C. §§4401-4403
Spectral Autonomy
DoD frames MOSA as five pillars resting on the statute. The fifth, certifying conformance, is co-equal: openness is verified, not asserted.

Where it sits

MOSA sits above the standard families as a requirement, not as a layer that generates them. It is one of two top-level drivers. The other is JADC2, an operational vision. Neither issues a technical specification. Standards bodies and program offices produce the specifications; MOSA is the legal reason a program adopts them.

The DoD open architecture ecosystem: two drivers over four familiesTwo non-technical drivers sit on top: MOSA, an acquisition mandate, and JADC2, an operational vision. Below them are four loosely coupled standard families: hardware (OpenVPX, SOSA, CMOSS, MORA, VICTORY, SpaceVPX, HOST), software and interfaces (FACE, DDS, OMS, UCI), the Government Reference Architectures (GARA, A-GRA, W-GRA, and AMS-GRA for mission systems), and PNT (pntOS, ASPN, R-EGI, and the PNT reference architecture). A solid border marks a multi-stakeholder consortium; a dashed border marks a single-service program office.MOSAacquisition mandateJADC2operational visionHARDWAREOpenVPXSOSACMOSSMORAVICTORYSpaceVPXHOSTSOFTWARE / INTERFACEFACEDDSOMSUCIGOVERNMENT REFERENCE ARCHITECTURESGARAA-GRAW-GRAAMS-GRA · mission systemsPOSITIONING, NAVIGATION & TIMINGpntOSASPNR-EGIPNT RAconsortium standardsingle-service program office
Spectral Autonomy
MOSA and JADC2 are drivers above four independently governed standard families; neither issues a technical specification.

Where this fits

FAQ

Is MOSA an architecture?
No. MOSA is an acquisition and design requirement. A program satisfies it by using modular designs and open interfaces, drawn from the standards and reference architectures that do define specifications.
Is MOSA required?
Yes, by law, for major defense programs, and it is applied to other programs to the maximum extent practicable.
Can a program satisfy MOSA without a reference architecture?
Yes. A program can meet MOSA through modular design, designated interfaces, and open standards alone. Adopting a Government Reference Architecture is one option, not a requirement.
Who owns MOSA?
The Office of the Under Secretary of Defense for Research and Engineering.

Sources